Batteries are each mainly constituted of a positive electrode, a negative electrode and an electrolytic solution. In order to prevent decrease of lifetime of batteries caused by leakage or vaporization of the electrolytic solution, containers of batteries have been desired to have structures of high rigidity, high sealing properties and excellent pressure resistance (e.g., cylindrical type, square type, coin type). Particularly these days, various forms have been required for batteries, and development of flat type batteries having large area has been made.
In this connection, solid batteries have been studied. As solid electrolytes contained in the solid batteries, various ceramics, inorganic conductive glasses (e.g., NASIKON, LISICON), and polymeric solid electrolytes composed of a solid solution of a polymer matrix and electrolytic salt have been studied. As for these materials, however, various problems have been pointed out. For example, the inorganic electrolytes show poor stability or they are restricted in the battery system. The polymeric solid electrolytes have low ionic conductivity or low diaphragm strength, though they show good processability. To cope with these problems, there have been disclosed, for example, polymeric solid electrolytes using polysiloxane (U.S. Pat. No. 5,123,512) or polyphosphazene (U.S. Pat. No. 4,840,856) as polymer matrix, and polymeric gel electrolytes using polyethylene oxide-crosslinked products (U.S. Pat. No. 5,037,712, No. 5,229,225, No. 5,009,970, No. 5,102,752), ethylene oxide copolymers (U.S. Pat. No. 4,818,644, Japanese Patent Laid-Open Publication No. 24164/1991), vinyl copolymers (Japanese Patent Laid-Open Publication No. 320781/1995) or epoxy resins (U.S. Pat. No. 5,006,431) as polymer matrix. These electrolytes, however, are still insufficient as polymeric solid electrolytes for batteries, from the viewpoints of ionic conductivity, film strength and stability.